The invention generally relates to surgical armrests.
A surgical armrest is used to support the arm of a surgeon or of a surgical assistant during an operation, in order to increase the precision of the surgeon's hand movements and to reduce fatigue. In view of the fact that a surgical intervention can last several hours and that the surgical personnel perform such an operation standing up, an armrest can contribute to ensuring that the precision of the manoeuvres performed by the operating surgeon does not decrease over time.
An armrest known from document U.S. Pat. No. 5,074,501 comprises an arm support which is secured on a carrying structure for the arm support. The arm support comprises a base and two pivot arms which together form a parallelogram. The two pivot arms are secured on the base in each case about a horizontally extending pivot axis, the two pivot axes of the two pivot arms being spaced apart from one another in the vertical direction.
The arm support is connected to the two pivot arms at their ends remote from the base. The height of the arm support is changed by the pivot arms being pivoted up or down.
The two pivot arms of the known armrest are assigned a control mechanism which makes it possible to pivot the pivot arms up or down and thus change the height of the arm support and to fix the pivot arms in a defined pivoting position and thus fix the arm support at a defined height. The control mechanism comprises a bar which moves at least in its longitudinal direction during pivoting of the two pivot arms.
On the upper and lower pivot arm, the bar is assigned securing clamps with which the movement of the bar can be blocked by tightening of the clamps, as a result of which the pivoting of the two pivot arms is blocked and the arm support can thus be secured at a defined height.
Such a control mechanism for lifting and lowering and for securing the arm support has the disadvantage that the securing clamps cannot be actuated by the hand of that arm resting in the arm support. For surgical applications in which the height of the arm support has to be adjusted frequently during an operation, this known armrest is only suitable to a limited degree because it is awkward to handles. In addition, it does not permit a controlled lowering of the arm support. Instead, there is a danger of the arm support dropping in an uncontrolled manner after the securing clamps have been released.
By contrast, the document EP-A-1 486 178 discloses a surgical armrest which, compared to the known armrest described above, has the advantage that the lifting, lowering and fixing of the armrest can be carried out using the arm that is received in the arm support. The control mechanism of this known surgical armrest comprises a force switch which, by means of different forces applied by the arm received in the arm support, switches an electric motor on and off, the electric motor driving a bar which allows the pivot arm to be pivoted up or down as a result of the bar being driven in or out.
The disadvantage of an electromechanical control mechanism of this kind is that a power supply is needed via a power cable. However, power cables constitute an obstacle in an operating theatre. In addition, in the event of a defect of the electric motor, for example due to overloading of the electric motor, the control mechanism does not function. If such a defect occurs during an operation, the operation has to be continued without an armrest.
In addition to drive mechanisms comprising electric motors, it has also been proposed, for example in document U.S. Pat. No. 6,102,344, to use hydraulic or pneumatic control mechanisms for adjusting the height of the arm support for surgical armrests. Like control mechanisms with electric motors, hydraulic or pneumatic control mechanisms have the disadvantage that they are not suitable for sterilization in an autoclave. Surgical instruments and appliances have to satisfy particularly stringent demands concerning their cleaning and sterilization in particular. A safe method of sterilization is the sterilization of instruments and appliances in an autoclave in which temperatures of over 120° C. and high steam pressures prevail. Electromotive, hydraulic or pneumatic parts cannot withstand these conditions.
A surgical armrest whose control mechanism operates mechanically is therefore desirable.
However, the armrest known from the document mentioned at the outset, and having a mechanically operating control mechanism, is, as has already been described, disadvantageous in terms of the lifting, lowering and fixing functions of the arm support.